General Circumscription, Distribution, and Classification of Ericales.  The Ericales is an order of about 4500 species of plants, traditionally arranged in eight families with about 160 genera (Bentham & Hooker, 1876; Drude, 1891;  Stevens, 1971;  Cronquist, 1981;  Dahlgren, 1983;  Thorne, 1992).  The eight "traditional" families include:  Cyrillaceae, Clethraceae, Grubbiaceae, Empetraceae, Epacridaceae, Pyrolaceae, Monotropaceae, and Ericaceae.  About 90% of the species belong to the Ericaceae (in the traditional sense) and most of the remainder to the Epacridaceae.  The other six families have only a little more than a hundred species in all.
     The Cyrillaceae (or Cyrilla Family) consists of 3 genera and l4 species, occurring in northern South America, Central America, the West Indies, and on the coastal plain of southeastern United States.  The Clethraceae (or Clethra Family) consists of 1 genus (Clethra) with about 65 species, occurring from tropical South America north to Mexico and southeastern United States, and also in tropical and subtropical southeastern Asia and the East Indies.  The Grubbiaceae (or Grubbia Family) consists of 1 genus (Grubbia) with 3 species, occurring only in the Cape region of South Africa.  The Empetraceae (or Crowberry Family) consists of 3 genera with about 5 species, occurring in the colder parts of the Northern Hemisphere, southern South America, and the coastal plain of southeastern United States.  The Epacridaceae (or Epacris Family) consists of 30 genera and 400 species, occuring primarily in Australia and New Zealand, but also reaching north to the Philippine Islands and mainland Southeastern Asia, and extending east to the Hawaiian Islands and Patagonia.  The Pyrolaceae (or Shinleaf Family) consists of 4 genera and about 45 species, occurring only in the Northern Hemisphere, and being most diverse in north temperate and boreal regions.  The Monotropaceae (or Indian Pipe Family) consists of 10 genera and 12 species, occurring mostly in temperate and boreal regions of the Northern Hemisphere, but one New World species ranges south nearly approaching the Equator in Colombia, and another Old World species nears the same latitude in the Malay Peninsula.  This family lacks chlorophyll (the green, food producing plant pigment) and is best known for the Indian Pipe genus (Monotropa).  The Ericaceae (or Heath Family), consisting of about 110 genera and 4000 species, is a diverse and geographically widespread family, occurring in temperate and cool tropical regions of all continents except Antarctica, and with greatest diversity in the montane Neotropics.  On a worldwide basis, many of the subgroupings within the family Ericaceae have radiated in distinct continental areas.  For example, the blueberry subfamily (Vaccinioideae), with over 1000 species, is most abundant in the tropics of the New World, Malaysia, and southeastern Asia.  There they usually occur as epiphytic shrubs in the cool, moist montane regions referred to as cloud forests, although a few species range into typically tropical situations.  The largest blueberry genus is Vaccinium with some 450 species, scattered throughout the world, but especially in southeast Asia and Malesia.  The heath subfamily (Ericoideae) is confined to Africa and Europe, with a proliferation of over 650 species of Erica in the Cape region of southern Africa.  The rhododendron subfamily (Rhododendroideae) consists primarily of the ornamental genus Rhododendron (including the azaleas), which contains 800-900 species in the mountains of Himalaya and western China, and on the island of New Guinea.  For more information about infrafamilial relationships within the Ericaceae, see Stevens (1995).
     In addition to the eight ericalean families, two others (Actinidiaceae and Diapensiaceae) are sometimes included within the Ericales by taxonomists.  If referred to the Ericales, the family Actinidiaceae (including the Saurauiaceae) would be the most archaic family, although anomalous with regards to several morphological features that could be easily accommodated in the order Theales.  The Diapensiaceae, although related to the Ericales, are removed from them because of a long list of differences, including embryological, staminal, and palynological features.  They too are probably better associated with the Theales.

     Current Overall Classification.  The classification systems of Ericalean families mentioned above have undergone many changes.  For example, the close relationships among the families Clethraceae, Ericaceae, and Epacridaceae have been evident for many years, with these three core families comprising more than 99% of the species of the order.  In recent years, however, there has been almost universal acceptance of the inclusion of Empetraceae and Cyrillaceae in the order, based especially on similarities in embryological and palynological features with those of the Ericaceae.  The Cyrillaceae was previously assigned to the Celastrales (and associated with the family Celastraceae).  The move to the Ericales has been generally accepted based on the accumulation of embryological and palynological studies.  Inclusion of the family Grubbiaceae has been fairly recent and there is still some question as to the exact relationship.  This family has often been placed in the order Santalales because of the structure of its pistil.  The ovary is inferior and as it begins its development, it is more or less two-locular.  As the ovary continues to mature it becomes unilocular with a standing, free-central placenta that bears two pendulous ovules.  This ovular structure is typically santalalean and completely atypical of the order Ericales.  There are, however, other features which cause it to be misplaced in the Santalales including anatomical differences, its autotrophic not parasitic habit, and no close relationships to any other family in the Santalales.  On the other hand, Grubbiaceae is distinctly ericoid in habit, embryological and palynological features, and in the similarly inverted position of the anthers during development.  Furthermore, the Monotropaceae and Pyrolaceae are often treated as Monotropoideae and Pyroloideae, respectively, or sometimes Monotropaceae is combined with Pyrolaceae.  The Pyrolaceae and Monotropaceae have the reduced embryo that so often accompanies parasitism or extreme mycotrophy in other groups and these relationships probably represent progressive stages in dependence on a mycorhizal fungus (Cronquist, 1981).
     Most recently, several studies, using cladistic techniques combined with new data from molecular and morphological systematics, have brought to light the need for major realignments at familial, subfamilial, tribal, and generic levels within Ericaceae (Anderberg, 1992, 1993;  Chase et al., 1993;  Judd and Kron, 1993;  Kron and Chase, 1993;  Kron, 1996, 1997;  Powell et al., 1996), and a new, higher-level classification of Ericaceae is currently being developed (Kron et al., in preparation).  These recent analyses have resulted in the conclusion that Ericaceae, as currently recognized, are paraphyletic and that Empetraceae, Epacridaceae, Monotropaceae, and Pyrolaceae are derivative lineages out of Ericaceae.  The exact relationships of Cyrillaceae, Clethraceae, and Actinidiaceae to Ericaceae are not certain at this time.

     Natural History of Neotropical Ericaceae.  In the Neotropics, the Ericaceae is concentrated in northwestern South America, in the cooler, moist, montane forest habitats between 1500 to 3000 m elevation, in primarily Colombia, Ecuador, Peru, and Venezuela, where nearly 50% of the species are epiphytes and approximately 94% are endemic (Luteyn, 1989).  There are 46 genera and about 900 species, with the largest genera including Cavendishia (150), Thibaudia (60), Psammisia (60), Vaccinium (ca. 48), Macleania (40), Disterigma (ca. 40), Gaylussacia (40), Gaultheria (37), and Ceratostema (34).  As a general rule, Ericaceae prefers partially exposed, moist, cool habitats and acid soils, and is closely associated with endotropic  mycorrhiza.  Ericads are often a prominent feature, dominating a major vegetation type of tropical montane regions known as the "ericaceous belt," and because of their sun-loving ecology, they are frequently found as pioneers near the craters of volcanoes or in recent landslide areas.  Pernettya prostrata forms carpets or creeping mats over many acres in the mountains of Mexico and Guatemala, as well as in the superpáramo at Nevado del Cocuy, Colombia (Luteyn, 1995).  In the high-elevation páramo, Pernettya resists trampling by cattle and is a successional species where grazing pressures increase.  It is frequently a pioneer species in new habitats created by road building, landslides, man-made fires, or volcanic activity.  It invades the páramo when the vegetation structure is low and open, but may remain when vegetation recovers.  Fire does not affect it directly, but actually helps spread it indirectly because it opens the vegetation (Pels & Verweij, 1992).  In Colombia, several ericads are found as epiphytes in the Pacific-coast mangroves.  In Venezuelan Guayana, Notopora schomburgkiana and Vaccinium spp. are typical elements in the sandy savanna shrubberies.  In the Neotropics in general, whenever the habitat becomes dry (for example, on the lee side of a mountain), more seasonal, or overly warm (tropical rainforest), Ericaceae disappears.
     Pollination of Ericacae in temperate and subtropical latitudes is primarily by bees, but in the Neotropics bird-pollination is the rule with hummingbirds acting as the main vector.  The flowers of many tropical American blueberries display a number of morphological features associated with pollination by hummingbirds:  the flowers are odorless (hummingbirds have no sense of smell);  flowers are relatively showy and their associated bracts often have contrasting colors in some shade of red, violet, or orange (which attract hummingbirds and are not particularly alluring to insects);  the corollas are regular and tubular in shape, with a constricted throat and spreading lobes (to exclude large insects);  the flowers are pendent or arching in habit and are arranged in open, elongate or few-flowered clusters (suited to hummingbirds which feed in flight);  a nectar secreting disc is located on top of the ovary at the base of the corolla (so the visitor needs a proboscis);  corolla tubes are thick and fleshy (to protect them from damage by a probing bill);  corollas correspond well to the size and proportions of the bills of visiting hummingbirds;  and sugar concentrations in the nectar fall into the range preferred by hummingbirds (total range 7-32%)(see Luteyn & Sylva S., 1999).  In connection with hummingbird pollination, nectar-thieving mites (Rhinoseius spp.) spend virtually their entire life cycle within the flowers of certain ericaceous hummingbird plants.  The mites depend not only upon the flowers as their source of nectar, but also upon the birds themselves, as their primary means of dispersal is on the bill or in the nasal cavities of  hummingbirds.  Dispersal of the small, light seeds in genera such as Bejaria, Lyonia, and Agarista, which have capsular fruits, is by wind;  however, most of the neotropical genera are berry-fruited and birds or small mammals probably act as agents of dispersal.

     General Economic Uses of Ericaceae.  In temperate regions, the number of ericad species used as ornamentals is inordinately large when compared with other plant groups of similar size.  Many of the most beautiful and prized horticultural plants throughout temperate regions of the world are found in the Ericaceae, notable examples being azaleas, rhododendrons, heaths, and heathers.  Some of the most spectacular bursts of color in the Spring are produced by these shrubs, and they are widely used not only for the beauty of their blooms, but also for the value of the many evergreen species as effective background shrubs.  Natural species are cultivated, and many hybrids have originated in cultivation (there are over 6000 cultivars of rhododendrons and azaleas).  Economically, in temperate regions, blueberries and cranberries are among the most important members of the family, being in constant demand.  Their commercial production is worth in excess of hundreds of millions of dollars annually.  The cultivated "highbush" blueberry, developed primarily from Vaccinium corymbosum and V. australe from eastern North America, has been domesticated entirely in the twentieth century.  Cranberries (Vaccinium macrocarpon) are a native North American plant that have been cultivated in New England since the early nineteenth century.  The major toxic substance in Ericaceae seems to be andromedotoxin.  This compound is known to occur in temperate species of Rhododendron, Leucothoe, Menziesia, Ledum, and Kalmia, and is probably more widespread than is now known.  The leaves, twigs, flowers, and pollen grains of these genera all contain andromedotoxin.  The course of the poisoning includes watering of the mouth, eyes and nose, loss of energy, vomiting, slow pulse, low blood pressure, lack of coordination, convulsions, and slow and progressive paralysis of arms and legs until death;  fatalities, however, are rare.  Humans can be poisoned by chewing on leaves and twigs, brewing "tea" from the leaves, or by sucking nectar from the flowers of these plants.  Poisonous honey, produced by bees after visiting large stands of Rhododendron, has been known for over twenty-four hundred years.  The honey is normally so bitter to the taste, however, that very little of it can be eaten.  Various species of Rhododendron and laurel (Kalmia) have long been known to be poisonous to domesticated animals (Luteyn, 1993).
     In the Neotropics, there are very few published accounts of uses of native Ericaceae.  Rhododendron simsii, native to Asia, is often cultivated terrestrially or in hanging baskets in the montane regions of Central America and northwestern South America. Vaccinium floribundum seems to be the most frequently used native species,  especially in Ecuador and Colombia, where the fruits are made into jams, drinks, and occasionally pies.  There are mixed reports, both in the literature and orally, as to the edible nature of the fruits of Pernettya in their natural habitats.  These reports range from statements that the fruits are sweet or edible, although somewhat insipid, to claims of intoxication (the Peruvian vernacular name "macha-macha" means drunkenness; cf. Macbride, 1959 and Sleumer, 1985) or hallucination after eating (see Luteyn, 1995).  Sleumer (pers. comm.) has eaten quantities of P. mucronata (in Argentina) and P. prostrata (in Venezuela) without side effects.  The nutritional and toxic aspects of the fruits of P. prostrata were reported by Gutiérrez (1989).  The symptoms of intoxication included salivation, vomiting, colic pains, depression of respiration, debility, collapse, and finally death.

     Acknowledgments.  Most of the information in this neotropical Ericaceae web site has been taken from and reflects both the published and unpublished research of James L. Luteyn gathered throughout the course of his career at The New York Botanical Garden since 1975. Grants from the National Science Foundation (DEB-8004283, DEB-7713455, DEB-8300080,  DEB-9628841, BSR-8318375, BSR-8317561, BSR-9024221, and BSR-9903719), Jessie Smith Noyes Foundation, the Andrew W. Mellon Foundation, the National Geographic Society, USAID, the USDA Agricultural Research Service, The Swedish Natural Science Research Council and the University of Aarhus (Denmark) have helped to sponsor the research. Olga Orozco helped with the initial data entry; Paola Pedraza is responsable for the current web site design. Any reuse of images or text from this website should be cleared with the authors.